1. Field of the Invention
The present invent ion relates to a three dimensional, support socket digitizing system, to be used primarily for the precise definition and formation of an effective, precision fitted, support socket of a clinical support device such as an orthotic brace and/or a prosthetic limb. In particular, the system can determine the precise shape of the three-dimensional object, such as the patient's body part, can be used conveniently and effectively with patients who cannot be readily moved or re-positioned into a cast or specialized laser/photographic scanner type device, can construct a support socket that effectively and evenly distributes pressure over the portion of the body being supported without substantial trial and error, and can accurately and precisely fit the support socket directly to the underlying skeletal structure.
Further, the present invention relates to a method of precisely forming a support socket of a clinical support device which effectively maps out the underlying skeletal structure at a support location, which provides for minimal trial and error, and which is comfortable and convenient to implement in a variety of situations and patient orientations so as to provide an appropriate pressure distributing support socket.
2. Description of the Related Art
In the prosthetic and orthotic fields of medicine, precise, customized clinical support devices, such as prosthetic limbs or orthotic braces, must often be constructed to correspond to unique and very specific shapes. In these applications, as in various other related and unrelated applications, the desire to determine the precise shape of a three-dimensional object, such as the body part to be supported, is quite necessary and often quite critical to the formation of an effective mold, model, or mating part, such as the support socket of the clinical support device. For example, in the case of a prosthetic limb, the support socket is generally adapted to be fitted over the terminal portion of a patient's limb in order to act as a replacement for the missing limb. As such, a precise fit is necessary because a substantial amount of constant pressure is going to be exerted on the terminal end of the limb as the clinical support device is utilized. Specifically, most portions of the body are not capable of withstanding constant focused pressure thereon for extended periods of time. This factor therefore necessitates that in the definition and formation of the support socket of the clinical support device, the pressure that will be exerted from the support device to the patient be spread out as much as possible, thereby preventing any concentrated or focused pressure on any one portion of the terminal end of the limb.
Currently in the art, it is substantially difficult to use known devices and methods to define the necessary configuration without substantial time and effort being put into initial molding and various revised moldings of the support socket of the clinical support device. This factor alone has made the conventional art relating to the formation of clinical support devices very specialized, with the practitioners often being highly skilled craftsmen with extensive years of training and experience. Specifically, because prior art systems and methods of defining the support socket are so imprecise, the extensive training and experience is necessary in order for the practitioner to get a feel for their patients' needs merely by viewing the patient and analyzing a conventional plaster type mold or photographically scanned image, and to recognize what the results of minor changes or modifications to the mold will be after viewing the pressure points which result after trial of an initial molded support socket. As is evident, such trial and error molding is not only time consuming and inconvenient for the patient, but can also become quite expensive due to the labor intensive nature of the work and the need to have a highly skilled practitioner. Accordingly, there is a need in the art to provide a system and method that can substantially facilitate the formation of a clinical support device while also increasing the precision of the form of an initially constructed support socket.
Continuing further with the example of the field of art relating to the formation of clinical support devices, there are presently a number of existing methods of shape capture that are utilized to define the support socket of a clinical support device. The first, most commonly used method simply involves the formation/molding of a plaster cast to capture the shape of the applicable body part. Once the plaster cast is taken, it is removed from the patient and filled with plaster to form a positive mold. The practitioner will then call upon their experience and/or best guess to guide them in adding or removing plaster by hand in order to modify the shape taken during casting and thereby create a final shape. As such, the final shape is truly a combination of the molded shape and the practitioner's skill and experience in determining where certain modifications should be made. A final plaster shape is then made and draped in some manner with heated plaster or laminate to create the finished support device. Unfortunately, however, in addition to being imprecise, and ineffective to provide any concrete information regarding pressure distribution, this conventional method can often be quite difficult or uncomfortable to implement. Specifically, because clinical support devices are often formed for use after a patient leaves the hospital and has undergone various procedures, it is often difficult to move a patient to a location where the molds can be made. Also, while the patient is in the hospital they may have various tubes or other devices connected with their body that make the formation of cast mold substantially difficult, if not completely impossible. Further, such conventional casting does not provide for any information regarding the three-dimensional shape of the limb in various flexed positions, a criteria that can be quite important to maintain the overall comfort and effectiveness of the clinical support device formed as the pressure points may change during flexing.
A second commonly utilized approach in the formation/definition of a support socket of a clinical support device includes the implementation of computer assisted formation with casting. Generally, in this method a plaster cast is taken of the patient in the same manner as the conventional casting method. The computerized imaging system is then used to take an image of the plaster cast either by mechanical or optical means. In particular, the cast is utilized to obtain the image because most conventional imaging systems require specific positioning of an object to be scanned, and often require extensive manipulation and re-orientation of the object being scanned. Once scanned by the computer, the practitioner can avoid the step of manually modifying the shape by making the estimated modifications utilizing the computer. From there, the final shape can be cut by a milling machine so as to form the physical model into a foam or plaster blank. This final foam or plaster shape is then draped in some manner with heated plaster or laminate to create the finished clinical support device to be used on the patient. As is evident from the description of this method, casting, a procedure which, as previously mentioned, can be inconvenient or difficult to accurately utilize, is still necessary to provide the initial frame work to be manipulated and captured as a computerized image. Further, the practitioner must still utilize trial and error along with their skill and experience to reconfigure the formed socket.
A third method associated with the creation of a clinical support device includes what is known as direct imaging. Direct imaging generally includes an optical sensor, which naturally takes a number of optical/picture images of the body parts to be supported, and often uses specialized laser guiding methods to define the precise area to be captured. Alternatively, some medical facilities utilize CT scans, MRI's or ultrasonic methods to accomplish the same results. These direct imaging devices, as well as those implemented in various other applications generally require a special facility or layout, and if some flexibility is available to probe the patient, the final image is often a result of a series of extrapolations taken from numerous reference points obtained through a light pen or other pointer. Further, regardless of the direct imaging system employed, once the computerized image is captured, the scanned image is merely utilized as a computer model to which the practitioner can make the estimated or "best guess" modifications for the formation of the foam plaster blank used in the fabrication of the finished appliance.
Lastly, perhaps the most popular method of making an initial molded socket for certain prosthetic and orthotic applications, involves the modification of a standard template socket in accordance with various circumference and length measurements taken of the patient. Such "fit to measurement" procedures, however, have a number of attendant drawbacks associated therewith. Specifically, taking such measurements provides no insight regarding the relative positioning and orientation of the measured sections relative to one another. As such, some trial and error is still required to properly orient the dimensions relative to one another to come up with an accurate three dimensional design that can ultimately be worn in a comfortable and effective manner. Moreover, such methods tend to be inaccurate due to the normal physical characteristics of the limb to be fitted. For example, conventional measurements are naturally constrained by the actual tissue and skin which forms the limb. Such physical characteristics, however, are susceptible to deformation, both when taking the measurement, and when the socket is actually implemented. As such, more than the conventional fit to measurement procedures are actually needed.
Accordingly, it would be highly beneficial to provide a system and method which is capable of effectively utilizing fixed, non-yielding reference positions, and orienting the three dimensional socket to correspond the actual skeletal structure of the patient instead of an approximation based upon an average specimen. Such a system would enhance the effectiveness of a fit to measurement technique by enabling a more accurate initial mold to be defined without extensive risks of deviation due to skin/tissue deformation during use. Indeed, the often lengthy and difficult, "trial and error" steps which must be performed after the initial volumetric measurements are made are virtually eliminated utilizing the system and method of the present invention to effectuate precise and accurate modifications.
Moreover, it is evident that the other alternative systems/methods which are currently employed in the art also have a number of serious drawbacks associated therewith. A first, and very significant drawback which is sought to be overcome with the system and method of the present invention relates to the inability of prior methods and devices to assist with the equalization of pressure throughout the finished support device, or at least to create smooth pressure variations from one area to the next. In fact, because as previously recited, a persons body parts are generally not capable of withstanding constant pressure, equalization of the pressure points throughout the finished support device, or at least the creation of smooth pressure variations from one area of the support socket to the next is one of the primary objectives in the field of prosthetics and orthotics, and has therefore turned many practitioners to exploring any method available to get some indication to assist with the determination of the necessary modifications. For example, practitioners utilizing the conventional methods attempt to "pre-load" the patient's musculature as much as possible in order to help distribute pressures equally in the final socket or appliance. This procedure, however, is substantially time consuming and in the end educated guesses, which are subject to human error, are still necessary. Accordingly, it is inevitable that when conventional pre-loading techniques are implemented, it is only later, during the modification and fitting stages, and after substantial trial and error, that the final equalization of surface pressures is accomplished. Further, such conventional methods much often rely on physical indicators such as reddening or blanching of the skin which is being supported to provide some indication of adjustments that should be made to appropriately equalize the pressure. Such physical indicators are not only imprecise, but can be painful to the patient. Still, however, because these pre-loading methods are better than nothing, the prior art methods which utilize casting are generally preferred over known direct imaging methodologies wherein no method for pre-loading the patient's musculature is available.
An additional drawback associated with all prior art methods of forming a support device is the fact that only one "snapshot" is taken from the patient. Because only one "snapshot", either through casting or direct imaging is available, the practitioner's ability to determine how the patient's flesh will deform and resist pressure during the modification phases or during a flexing of the patient's body is substantially limited.
Still another drawback associated with conventional devices relates to site and circumstance restrictions. Specifically, utilizing conventional devices/methods the practitioner is generally restricted to a particular location or facility wherein the plaster cast can be appropriately taken and maintained, or to a particular location where the large, often highly expensive direct imaging device is located. Further, it is a common occurrence regarding postoperative patients that casting will be unavailable, especially when a body-jacket is necessary, because of the intravenous tubes, drains, and other equipment that must be left undisturbed and connected with the patient. Such circumstances similarly prevent the direct imaging methods, as the various equipment connected with the patient can significantly interfere with the taking of an accurate image. Also, with regard to direct imaging, the most common of which are optics based, certain shadowing is often experienced as the scanner cannot appropriately obtain an image of hidden areas, such as the patient's ischium or ramus which are critical to a correct fit for an above the knee support device.
Yet another drawback associated with conventional methods of forming a clinical support devices relates to the axial limitations. Generally, with most conventional methods, there is an implied single axis center line which must be given consideration when forming the support device. Unfortunately, however, in some circumstances such as during the formation of an ankle-foot orthosis, it may be impossible for the patient to have a single centerline running through the body portion to be captured. Similarly, the computer assisted capture methods are generally ineffective when a single center line cannot be drawn through the cast or through the entire body portion to be scanned.
Accordingly, there is a substantial need in the art for an improved digitizing system which enables precise surface images of a three-dimensional object, such as a body part of an individual, to be conveniently and precisely determined in virtually any circumstance or patient location. Additionally, it would be highly beneficial to provide a digitizing system and method of manufacturing a support device which is able to provide for immediate modification, provide precise images, and enable the construction of a precise pressure distributing support device without substantial trial and error, or guess work on the part of the practitioner. Also, such a device should be capable of achieving an accurate skeletal fit in order to eliminate deviations due to casting or measuring over deformable skin/tissue regions. The device of the present invention is designed precisely to meet these needs as well as the needs of other imaging applications wherein a quick, convenient, yet precise three dimensional image must be determined and/or when precise determination of the deformability of a three dimensional object under pressure is necessary.